The technique of fastening a workpiece by using a fastener (a fastening member) such as a bolt and a rivet is used for assembling an aircraft. When a part of the main wing of the aircraft should be fastened by using the fastener, a fastening portion is sealed to prevent fuel leakage.
A method of fastening a workpiece of composite members such as fiber reinforced plastics will be described with reference to FIG. 1 to FIG. 6.
As shown in FIG. 1, a workpiece 3 contains composite members 1 and 2 which are stacked. A hole 4 with a countersink is formed to pass from a surface 5 on one side of the work 3 to a rear surface on the other side. The countersink of the hole 4 is arranged on the side of the surface 5. The workpiece 3 has a countersink wall 7 which surrounds the countersink. After the hole 4 with the countersink is formed, the workpiece 3 is cleaned to remove burr produced in case of forming the the hole 4 with the countersink.
FIG. 2 shows a fastener 8 as a fastening member to fasten the workpiece 3. For example, the fastener 8 is a hack tight fastener. The fastener 8 includes a countersunk bolt 9 and a sleeve 10. The sleeve 10 has a pipe shape and the countersunk bolt 9 is inserted into the sleeve 10. The countersunk bolt 9 includes a countersunk head 11, a circular column section 12, and a screw section 13. The countersunk head 11 has a head surface 14 and a head side surface 18. The head side surface 18 is formed to have a shape of a side surface of a circular truncated cone. The circular column section 12 is arranged between the countersunk head 11 and the screw section 13. A screw is not formed in the circular column section 12. The screw section 13 has an end surface 15. The head surface 14 and the end surface 15 are arranged at both ends of the fastener 8 in the axial direction. The sleeve 10 covers the circular column section 12. A part of the circular column section 12 which is near the countersunk head 11 is exposed from the sleeve 10. The sleeve 10 includes a countersink section 16 disposed on the side of the countersunk head 11 and a circular cylinder section 17 arranged on the side of the screw section 13. The countersink section 16 is conically formed.
As shown in FIG. 3, until the countersink section 16 hits against the countersink wall 7, the fastener 8 is pushed into the hole 4 with the countersink. In a condition that the countersink section 16 contacts the countersink wall 7, the countersink head 11 protrudes from the surface 5 and the screw section 13 protrudes from the surface 6.
As shown in FIG. 4, an impact force is repeatedly applied to the head surface 14 by using an air hammer 19 so that the fastener 8 is hit into the hole 4.
As shown in FIG. 5, the impact force is repeatedly given to the head surface 14 by using the air hammer 19, until the fastener 8 is located in the workpiece 3, that is, until the countersink head 11 hits against the countersink wall 7 through the countersink section 16. Here, an operator determines in sound that the fastener 8 is located and stops the application of the impact force by the air hammer 19.
As shown in FIG. 6, a nut 20 is attached to the screw section 13 to fasten the composite members 1 and 2.
Here, in order to seal the fastening section, a sealant is applied on the countersink section 16, the circular cylinder section 17 and the head side surface 11 with a brush in handwork. It is visually confirmed that the sealant is completely applied. When the sealant is applied in handwork, the work time takes greatly and it is difficult to stabilize the quality.
In relation to the above, Patent Literature 1 discloses a sealant applying apparatus which applies the sealant in a rivet hole.
Also, Patent Literature 2 discloses a riveting machine to combine a plurality of fastened members with a rivet. With reference to FIG. 7, a chuck mechanism of the riveting machine will be described. A rivet inserting unit of the riveting machine includes a piston member 100 disposed to be slidable and a rivet pushing rod 102 attached to the piston member 100. The rivet pushing rod 102 includes an attaching section 103. The piston member 100 includes an attachment hole 101 which has substantially the same shape as the attaching section 102 and engages with the attaching section 103. The chuck mechanism 105 is disposed at tip of the rivet pushing rod 102. The chuck mechanism 105 is made openable and closable by being biased by a coil spring 104, and hold an axis section of the rivet in the closed state.